I wonder if someone as implemented a parametric equalizer similar to the ones you find on mixer : like three band LOW MID HIGH, with -/+ X dB so that when everything is +0 dB, the output is flat and similar to input.
And eventually with Q/curve/spectral transistion parameters ?
I know this is a very large question and that there might be a lot of different implementations, but I wondered if there are "standard" solutions.